arXiv subjects

Jun Hu

Publications and source records attributed to Jun Hu.

At least 73 records · Page 4Linked to original sources

arXiv2025

Nature of magnetic exchange interactions in kagome antiferromagnets FeGe and FeSn

Magnetic exchange interactions (MEIs) in kagome magnets exhibit rich features due to the interplay of charge, spin, orbital and lattice degrees of freedom, giving rise to a variety of exotic quantum states. Through first-principles calculations, we systematically investigate the MEIs in kagome antiferromagnets FeGe and FeSn. While the antiferromagnetic order originates from the interlayer coupling between neighboring kagome layers, Fe atoms within each kagome layer couple ferromagnetically, driven by the competition between ferromagnetically favorable direct MEIs and antiferromagnetically favorable Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. The stronger direct MEIs but weaker RKKY interactions in FeGe result in a substantially higher Néel temperature with respect to FeSn. Interestingly, the nearest neighboring exchange energy in both materials approximately linearly depends on the Fe-Fe bond length, so that moderate compressive strain can significantly enhance their Néel temperatures.

cond-mat.mtrl-sci↗

arXiv2025

The Hu-Zhang element for linear elasticity on curved domains

This paper extends the Hu-Zhang element for linear elasticity to curved domains, preserving strong symmetry and H(div)-conformity. The non-polynomial structure of the curved Hu-Zhang element makes it difficult to analyze the stability, which is overcome by establishing a novel inf-sup condition. Optimal convergence rates are achieved for all variables except for the stress in the $L^2$-norm. This suboptimality originates from the fact that the divergence space of the curved Hu-Zhang element is not contained in the discrete displacement space, which is improved by local $p$-enrichment on boundary elements. Two numerical experiments validate the theoretical results.

math.NA↗

arXiv2025

Beyond Divergence: Characterizing Co-exploration Patterns in Collaborative Design Processes

Exploration is crucial in the design process and is known for its essential role in fostering creativity and enhancing design outcomes. Within design teams, exploration evolves into co-exploration, a collaborative and dynamic practice that this study aims to unpack. To investigate this experience, we conducted a longitudinal observational study with 61 students across 16 design teams. Over five months of weekly diary-interviews, we uncovered the intricate dynamics of co-exploration. Our main contribution is a four-dimensional framework that identifies five distinct patterns of co-exploration activities. Our findings reveal how co-exploration emerges across various activities throughout the design process, demonstrating its role in different team interactions. It fosters a sense of togetherness, keeping design teams open-minded and engaged. This engagement cultivates collective intelligence, enabling teams to actively share knowledge, build upon each other's ideas, and achieve outcomes beyond individual contributions. Our study underscores the value of co-exploration, suggesting that it reflects the trajectory of design success and warrants further research. We also provide actionable insights, equipping future practitioners with strategies to enhance co-exploration in design collaborations.

cs.HC↗

arXiv2025

A direct finite element method for elliptic interface problems

In this paper, a direct finite element method is proposed for solving interface problems on unfitted meshes. This new method treats the two interface conditions as an $H^{\frac12}(Γ)\times H^{-\frac12}(Γ)$ pair for the mutual interaction across the interface, rather than the jumps of variables. A simple and straightforward finite element method is proposed based on this approach. This method solves the interface problem using conforming finite elements in one subdomain and conforming mixed finite elements in the other, with a natural integral term accounting for mutual interaction. Under reasonable assumptions, this direct finite element method is proved to be well-posed with an optimal a priori error analysis. Moreover, a simple lowest-order direct finite element method, using the linear element and the lowest-order Raviart-Thomas element, is analyzed to achieve the optimal a priori error estimate by verifying the aforementioned assumptions. Numerical tests are provided to confirm the theoretical results and the effectiveness of the direct finite element method.

math.NA↗

arXiv2025

Towards Smart Workplaces: Understanding Mood-Influencing Factors of the Physical Workspace in Collaborative Group Settings

Group mood plays a crucial role in shaping workspace experiences, influencing group dynamics, team performance, and creativity. The perceived group mood depends on many, often subconscious, aspects such as individual emotional states or group life, which make it challenging to maintain a positive atmosphere. Intelligent technology could support mood regulation in physical office environments, for example, as adaptive ambient lighting for mood regulation. However, little is known about the relationship between the physical workspace and group mood dynamics. To address this knowledge gap, we conducted a qualitative user study (N=8 workgroups and overall 26 participants) to explore how the physical workspace shapes group mood experiences and investigate employees' perspectives on intelligent mood-aware technologies. Our findings reveal key factors influencing group mood, and participants' expectations for supportive technology to preserve privacy and autonomy. Our work highlights the potential of adaptive and responsive workspaces while also emphasizing the need for human-centered, technology-driven interventions that benefit group well-being.

cs.HC↗

arXiv2025

Optimality of adaptive $H(\operatorname{div}\operatorname{div})$ mixed finite element methods for the Kirchhoff-Love plate bending problem

This paper presents a reliable and efficient residual-based a posteriori error analysis for the symmetric $H(\operatorname{div}\operatorname{div})$ mixed finite element method for the Kirchhoff-Love plate bending problem with mixed boundary conditions. The key ingredient lies in the construction of boundary-condition-preserving complexes at both continuous and discrete levels. Additionally, the discrete symmetric $H(\operatorname{div}\operatorname{div})$ space is extended to ensure nestedness, which leads to optimality for the adaptive algorithm. Numerical examples confirm the effectiveness of the a posteriori error estimator and demonstrate the optimal convergence rate under adaptive refinements.

math.NA↗

arXiv2025

Discretizing linearized Einstein-Bianchi system by symmetric and traceless tensors

The Einstein-Bianchi system uses symmetric and traceless tensors to reformulate Einstein's original field equations. However, preserving these algebraic constraints simultaneously remains a challenge for numerical methods. This paper proposes a new formulation that treats the linearized Einstein-Bianchi system (near the trivial Minkowski metric) as the Hodge wave equation associated with the conformal Hessian complex. To discretize this equation, a conforming finite element conformal Hessian complex that preserves symmetry and traceless-ness simultaneously is constructed on general three-dimensional tetrahedral grids, and its exactness is proven.

math.NA↗

arXiv2025

DGP: A Dual-Granularity Prompting Framework for Fraud Detection with Graph-Enhanced LLMs

Real-world fraud detection applications benefit from graph learning techniques that jointly exploit node features, often rich in textual data, and graph structural information. Recently, Graph-Enhanced LLMs emerge as a promising graph learning approach that converts graph information into prompts, exploiting LLMs' ability to reason over both textual and structural information. Among them, text-only prompting, which converts graph information to prompts consisting solely of text tokens, offers a solution that relies only on LLM tuning without requiring additional graph-specific encoders. However, text-only prompting struggles on heterogeneous fraud-detection graphs: multi-hop relations expand exponentially with each additional hop, leading to rapidly growing neighborhoods associated with dense textual information. These neighborhoods may overwhelm the model with long, irrelevant content in the prompt and suppress key signals from the target node, thereby degrading performance. To address this challenge, we propose Dual Granularity Prompting (DGP), which mitigates information overload by preserving fine-grained textual details for the target node while summarizing neighbor information into coarse-grained text prompts. DGP introduces tailored summarization strategies for different data modalities, bi-level semantic abstraction for textual fields and statistical aggregation for numerical features, enabling effective compression of verbose neighbor content into concise, informative prompts. Experiments across public and industrial datasets demonstrate that DGP operates within a manageable token budget while improving fraud detection performance by up to 6.8% (AUPRC) over state-of-the-art methods, showing the potential of Graph-Enhanced LLMs for fraud detection.

cs.LG↗

arXiv2025

Towards Emotion Co-regulation with LLM-powered Socially Assistive Robots: Integrating LLM Prompts and Robotic Behaviors to Support Parent-Neurodivergent Child Dyads

Socially Assistive Robotics (SAR) has shown promise in supporting emotion regulation for neurodivergent children. Recently, there has been increasing interest in leveraging advanced technologies to assist parents in co-regulating emotions with their children. However, limited research has explored the integration of large language models (LLMs) with SAR to facilitate emotion co-regulation between parents and children with neurodevelopmental disorders. To address this gap, we developed an LLM-powered social robot by deploying a speech communication module on the MiRo-E robotic platform. This supervised autonomous system integrates LLM prompts and robotic behaviors to deliver tailored interventions for both parents and neurodivergent children. Pilot tests were conducted with two parent-child dyads, followed by a qualitative analysis. The findings reveal MiRo-E's positive impacts on interaction dynamics and its potential to facilitate emotion regulation, along with identified design and technical challenges. Based on these insights, we provide design implications to advance the future development of LLM-powered SAR for mental health applications.

cs.HC↗

arXiv2025

User Concerns Regarding Social Robots for Mood Regulation: A Case Study on the "Sunday Blues"

While recent research highlights the potential of social robots to support mood regulation, little is known about how prospective users view their integration into everyday life. To explore this, we conducted an exploratory case study that used a speculative robot concept "Mora" to provoke reflection and facilitate meaningful discussion about using social robots to manage subtle, day-to-day emotional experiences. We focused on the "Sunday Blues," a common dip in mood that occurs at the end of the weekend, as a relatable context in which to explore individuals' insights. Using a video prototype and a co-constructing stories method, we engaged 15 participants in imagining interactions with Mora and discussing their expectations, doubts, and concerns. The study surfaced a range of nuanced reflections around the attributes of social robots like empathy, intervention effectiveness, and ethical boundaries, which we translated into design considerations for future research and development in human-robot interaction.

cs.HC↗

arXiv2025

A nodal basis for the $C^1$-$P_{33}$ finite elements on 5D simplex grids

We construct a nodal basis for the 5-dimensional $C^1$ finite element space of polynomial degree $33$ on simplex grids, where the finite element functions are $C^1$ on the 6 4D-simplex faces, $C^2$ on the 15 face-tetrahedra, $C^4$ on the 20 face-triangles, $C^8$ on the 15 edges, and $C^{16}$ at the 6 vertices, of a 5D simplex.

math.NA↗

arXiv2025

LLaDA-V: Large Language Diffusion Models with Visual Instruction Tuning

In this work, we introduce LLaDA-V, a purely diffusion-based Multimodal Large Language Model (MLLM) that integrates visual instruction tuning with masked diffusion models, representing a departure from the autoregressive paradigms dominant in current multimodal approaches. Built upon LLaDA, a representative large language diffusion model, LLaDA-V incorporates a vision encoder and MLP connector that projects visual features into the language embedding space, enabling effective multimodal alignment. Our empirical investigation reveals several intriguing results: First, LLaDA-V demonstrates promising multimodal performance despite its language model being weaker on purely textual tasks than counterparts like LLaMA3-8B and Qwen2-7B. When trained on the same instruction data, LLaDA-V is highly competitive to LLaMA3-V across multimodal tasks with better data scalability. It also narrows the performance gap to Qwen2-VL, suggesting the effectiveness of its architecture for multimodal tasks. Second, LLaDA-V achieves state-of-the-art performance in multimodal understanding compared to existing hybrid autoregressive-diffusion and purely diffusion-based MLLMs. Our findings suggest that large language diffusion models show promise in multimodal contexts and warrant further investigation in future research. Project page and codes: https://ml-gsai.github.io/LLaDA-V-demo/.

cs.LG↗

arXiv2025

Synergizing LLMs with Global Label Propagation for Multimodal Fake News Detection

Large Language Models (LLMs) can assist multimodal fake news detection by predicting pseudo labels. However, LLM-generated pseudo labels alone demonstrate poor performance compared to traditional detection methods, making their effective integration non-trivial. In this paper, we propose Global Label Propagation Network with LLM-based Pseudo Labeling (GLPN-LLM) for multimodal fake news detection, which integrates LLM capabilities via label propagation techniques. The global label propagation can utilize LLM-generated pseudo labels, enhancing prediction accuracy by propagating label information among all samples. For label propagation, a mask-based mechanism is designed to prevent label leakage during training by ensuring that training nodes do not propagate their own labels back to themselves. Experimental results on benchmark datasets show that by synergizing LLMs with label propagation, our model achieves superior performance over state-of-the-art baselines.

cs.CL↗

arXiv2025

DarkDiff: Advancing Low-Light Raw Enhancement by Retasking Diffusion Models for Camera ISP

High-quality photography in extreme low-light conditions is challenging but impactful for digital cameras. With advanced computing hardware, traditional camera image signal processor (ISP) algorithms are gradually being replaced by efficient deep networks that enhance noisy raw images more intelligently. However, existing regression-based models often minimize pixel errors and result in oversmoothing of low-light photos or deep shadows. Recent work has attempted to address this limitation by training a diffusion model from scratch, yet those models still struggle to recover sharp image details and accurate colors. We introduce a novel framework to enhance low-light raw images by retasking pre-trained generative diffusion models with the camera ISP. Extensive experiments demonstrate that our method outperforms the state-of-the-art in perceptual quality across three challenging low-light raw image benchmarks.

cs.CV↗

arXiv2025

Distributed Stochastic Optimization for Non-Smooth and Weakly Convex Problems under Heavy-Tailed Noise

In existing distributed stochastic optimization studies, it is usually assumed that the gradient noise has a bounded variance. However, recent research shows that the heavy-tailed noise, which allows an unbounded variance, is closer to practical scenarios in many tasks. Under heavy-tailed noise, traditional optimization methods, such as stochastic gradient descent, may have poor performance and even diverge. Thus, it is of great importance to study distributed stochastic optimization algorithms applicable to the heavy-tailed noise scenario. However, most of the existing distributed algorithms under heavy-tailed noise are developed for convex and smooth problems, which limits their applications. This paper proposes a clipping-based distributed stochastic algorithm under heavy-tailed noise that is suitable for non-smooth and weakly convex problems. The convergence of the proposed algorithm is proven, and the conditions on the parameters are given. A numerical experiment is conducted to demonstrate the effectiveness of the proposed algorithm.

math.OC↗

arXiv2025

The High Voltage Splitter board for the JUNO SPMT system

The Jiangmen Underground Neutrino Observatory (JUNO) in southern China is designed to study neutrinos from nuclear reactors and natural sources to address fundamental questions in neutrino physics. Achieving its goals requires continuous operation over a 20-year period. The small photomultiplier tube (small PMT or SPMT) system is a subsystem within the experiment composed of 25600 3-inch PMTs and their associated readout electronics. The High Voltage Splitter (HVS) is the first board on the readout chain of the SPMT system and services the PMTs by providing high voltage for biasing and by decoupling the generated physics signal from the high-voltage bias for readout, which is then fed to the front-end board. The necessity to handle high voltage, manage a large channel count, and operate stably for 20 years imposes significant constraints on the physical design of the HVS. This paper serves as a comprehensive documentation of the HVS board: its role in the SPMT readout system, the challenges in its design, performance and reliability metrics, and the methods employed for production and quality control.

physics.ins-det↗

arXiv2025

Workshop on Aesthetics of Connectivity for Empowerment at ACM Designing Interactive Systems 2024

Connectivity enabled by technologies such as the Internet of Things, Artificial Intelligence, Big Data, and Cloud Computing is rapidly transforming our interactions with the world and with each other. It reshapes social interactions, fostering collaboration, creativity, and unprecedented access to information and resources. However, this connected world and era demand innovative design approaches that harmonize technical functionality with human-centered values. We have run a series of workshops at different conferences, trying to engage the participants in discussions about the related challenges and opportunities, of digital art [1] and aesthetics [2] to AI-driven creativity [3] and their functional aspects in healthcare [1] and empowerment [2, 3]. We want to focus further on the intersection of these challenges where we see opportunities: leveraging aesthetics and connectivity as catalysts for empowerment.

cs.HC↗

arXiv2025

Petting Pen for Stress Awareness and Management in Children

We found that children in elementary school often experience stress during task performance. Limited coping skills and lack of stress awareness restrict children's ability to manage their stress. Many designs and studies have proposed different stress detection and intervention solutions. Still, they often overlook the potential of enhancing everyday objects and actively sensing stress-related behavioral data during human-product interaction. Therefore, we propose Petting pen as an interactive robotic object for children to manage their stress during task performance. It detects and validates stress and further intervenes in stress during a process of natural writing and relaxation interactions. The design is an iteration based on our previous research results of a stress-aware pen, enhanced with tactile needs, robotic interaction, and integration of behavioral and bio-sensing capabilities. Petting pen is supposed to bridge the gap between robots and everyday objects in mental health applications for children.

cs.HC↗